Evidence of taxonomic but not functional diversity extinction debt in bird assemblages in an urban area in the Cerrado hotspot

Land use changes can drive distinct spatial and temporal shifts in community structure. In urban areas, the historical trajectory of land use changes can create a time lag between landscape modification and their impact on species, potentially leading to an extinction debt. The detection of an extinction debt may be crucial for mitigating taxonomic and functional diversity losses in the future. Here, we investigated the effect of historical changes in landscape composition on bird assemblages in a city from central-west Brazil (Campo Grande). We evaluated whether taxonomic (species richness) and functional diversity (functional divergence) of bird assemblages are explained by present-day and/or past landscape composition. We used a dataset of birds sampled in 61 local landscapes, each of them with 16 ha, during the months of February to March in 2016. We quantified the proportions of native forest and urban infrastructure for three different years (1985, 2000 and 2016). Then, we selected 30 local landscapes that have experienced an increase in urbanization throughout the years. Bird species richness was explained by the percentage of urban infrastructure in the past (year 2000), suggesting the presence of a taxonomic extinction debt in Campo Grande. On the other hand, we didn’t find evidence of an extinction debt for bird functional diversity, as the null model was as plausible as the other selected models. The protection and restoration of native vegetation may improve the quality of urban areas and prevent the payment of this extinction debt.